1. Field of the Invention
The present invention relates to a communication device, a method for controlling the communication device and a program thereof.
2. Description of the Related Art
Conventionally, Quality of Service (QoS) has been known as a technique for securing communication quality on a network such as a Local Area Network (LAN). U.S. Patent Application Publication No. 2006/0002353 discusses a configuration to perform QoS control in which a virtual Local Area Network (VLAN) tag is set based on a Type of Service (TOS) that is preliminarily decided by a user according to a correspondency table between the TOS and the VLAN tag. Japanese Patent Laid-open No. 2007-174704 discusses a configuration to perform QoS control in which a communication port that is used by an application is monitored and a transmission output is powered up when a specific port, which is preliminarily determined by the user, is used.
However, in the above-discussed conventional techniques, the QoS control is not performed in a connection in a Transmission Control Protocol (TCP). Therefore, when other communications having a priority higher than, for example, that of a communication without the QoS control, the connection in the TCP sometimes results in failure or a delay. However, if, for example, a higher priority is set to all of the packets that are used in the connection in the TCP, communication load of the network increases.